Divide granulated sugar into two portions of 1/2 cup each.

Heat one portion (1/2 cup) of sugar in a saucepan over medium heat to make caramel.

Watch the sugar closely as it melts; swirl the pan occasionally to ensure even heating.

Continue heating until the sugar turns a rich amber color, indicating it has caramelized.

Carefully pour the hot caramel into individual ramekin cups, dividing it evenly among 5 ramekins.

Allow the caramel to cool and harden, forming the base of the flan.

In a separate pan, combine whipping cream and half-and-half.

Heat the milk mixture over low heat until it is barely simmering, being careful not to boil.

If adding coffee flavor, stir in instant coffee granules to the warm milk mixture.

Add the remaining 1/2 cup of granulated sugar to the milk mixture and stir until fully dissolved.

In a separate bowl, slightly beat the eggs.

Gradually pour a small amount of the warm milk mixture into the beaten eggs, whisking constantly to temper the eggs and prevent them from cooking.

Pour the warm egg mixture back into the pan with the remaining milk mixture and continue whisking to combine.

Stir in vanilla extract and salt.

Pour the custard mixture into the caramel-lined ramekins, filling each one nearly to the top.

Place the ramekins in a large baking pan (e.g., 13x9 inch).

Carefully pour hot water into the baking pan around the ramekins, creating a bain-marie (water bath). The water level should reach about 1 inch up the sides of the ramekins.

Bake in a preheated 325°F (160°C) oven for approximately 45 minutes.

To check for doneness, gently shake one of the ramekins; the flan should be set around the edges but still slightly wobbly in the center.

Remove the baking pan from the oven and carefully remove the ramekins from the water bath.

Allow the flans to cool completely at room temperature, then refrigerate for at least 2 hours to chill thoroughly.

To unmold, run a thin knife around the edge of each flan to loosen it from the ramekin.

Invert each flan onto a serving plate, allowing the caramel sauce to flow over the custard.

Serve chilled and enjoy.